Using multiple entries as Input Parameter in Sql Script

Hi,

I have a requirement to do a selection on a table to fetch MATNR realated information which is passed to the model as input parameter.

I have a declared an input parameter with multiple entries checked in my model and my query is as below.

select "MATNR","KNUMH" from "A600" where "MATNR" in (:P_Matnr);

P_Matnr => MAT1,MAT2,MAT3

But this query is not returning any values